Artikel 22-1

(1). Two gate valves controlled from the working deck of the chute instead of the non- return valve with a positive means of closing from a position above the freeboard deck which comply with the following requirements are acceptable:
(a) the lower gate valve shall be controlled from a position above the freeboard deck. An interlock system between the two valves shall be arranged;
(b) the inboard end shall be located above the waterline formed by an 8.5° heel to port or starboard at a draft corresponding to the assigned summer freeboard, but not less than 1,000 mm above the summer waterline. Where the inboard end exceeds 0.01L above the summer waterline, valve control from the freeboard deck is not required, provided the inboard gate valve is always accessible under service conditions; and
(c) alternatively, the upper and lower gate valves may be replaced by a hinged weathertight cover at the inboard end of the chute together with a discharge flap. The cover and flap shall be arranged with an interlock so that the discharge flap cannot be operated until the hopper cover is closed.
(2). The entire chute, including the cover, shall be constructed of material of substantial thickness.
(3). The controls for the gate valves and/or hinged covers shall be clearly marked: “Keep closed when not in use”.
(4). Where the inboard end of the chute is below the freeboard deck of a passenger ship or the equilibrium waterlines of a cargo ship to which damage stability requirements apply, then:
(a) the inboard end hinged cover/valve shall be watertight;
(b) the valve shall be a screw-down non-return valve fitted in an easily accessible position above the deepest load line; and
(c) the screw-down non-return valve shall be controlled from a position above the bulkhead deck and provided with open/closed indicators. The valve control shall be clearly marked: “Keep closed when not in use”.